Improvement in steam-engines



H. P. CASE.l l Steam-lingim.

N0, 164,804l Patentedjune 22,1875

YHE GRAPHIC COAPHOTO -LITH.39& 4-1 PARK PLACEJ'LY.

UNITED STaTEs PATENT QEEICE.

HIRAM P. OASE, OF DETROIT, MICHIGAN.

IMPRovEMi-:NT iN sTEAM-ENGiNEs.

Specification forming part of Letters Patent No. 164,804, dated June 22, 1875; application filed December 30, 1874.

To all whom it may concern Be it known that I, HIRAM P. CASE, Vof Detroit, in the county of Wayne and State of Michigan,l1ave invented an Improvement in Steam-Engines, of which the following is a specification The object of my invention is to provide a steam-engine with a supplementary valve, moving in unison with the steam valve or valves, for passing a portion ot the exhaust steam from the exhaust side of the piston to the steam side just beforetlie completion of each stroke, to fill the side pipes,W passage, and clearance with exhaust steam, and thereby save that volume of live steam, and at the same time to reduce the compression at the termination of each stroke. The valve may be Worked by an arm on the stem of the slidevalve, if the engine be fitted with one, or by a separate eccentric.

Figure 1 is a longitudinal vertical section of a steam-engine fitted with my improvement, showing the piston at mid-stroke. Fig. 2 is a similar view, but showing the piston nearly at the end of its stroke in the reverse direction. Fig. 3 is a sectional end elevation.

In the drawing, A represents a steam-cylinder, having the usual steam-ports a a, and exhaust-port b. B isthe piston. C is the steamchest, tted with an ordinaryslide-valve, D. Above the chest I bolt on the cap thereof a cylindrical steain-chest, E, fitted with a pistonvalve, F, whose stem G is connected by an arm, H, with the stem ofthe main valve D. Under the cylindrical bore of the chest E two passages, c, are cored in it, one leading to each end from a central port in the chest, each passage having its own port. To balance the valve F, a central belt, d, is cored around the chest E. A pipe, e, is tapped into the 'end of each passage c, and its other end into the side pipe or passage a of the steam-cylinder. One of the pipes c is provided With a cock, j'. During the time the pistonkis moving, .the val-ve F covers one of the ports c, as seen in Fig. 1, until just as the piston vis about to complete its stroke, when the valve F, moving with the main valve in a reverse direction to the piston, will uncover the ports c, (the main valve having covered both steam-ports a,) and a portion of the exhaust steam, or that Which is'on the exhaust side, Will pass through the pipe c into the chest E, through the port c, around the valve F, thence through the other passage c and pipe e into the steampassage a, filling it and the clearance With exhaust steam, saving an equal volume ot' live steam, and reducing the compression. At the end of the stroke the valve F will again cover the ports. The volume of steam so passing through the pipes may be regulated by the cock f.

On engines having other than sli|devalves. the supplementary valve may be actua-ted by an independent eccentric.

What I claim as my invention, and desire to secure by Letters Patent, is

The combination, with a steam-engine, of an Y independent valve and valve-chest and pipes, forJU transferring a portion of the exhaust steam to the steam side of the piston, at or near the completion of each stroke of the piston, substantially as described. .t

. HIB-AM P. CASE.

Witnesses:

H. S. SPRAGUE, H. F. EBERTs. 

